Laser Powder Bed Fusion of ODS 14YWT from Gas Atomization Reaction Synthesis Precursor Powders

Laser powder bed fusion (LPBF) additive manufacturing (AM) is a promising route for the fabrication of oxide dispersion strengthened (ODS) steels. In this study, 14YWT ferritic steel powders were produced by gas atomization reaction synthesis (GARS). The rapid solidification resulted in the formation of stable, Y-containing intermetallic Y2Fe17 on the interior of the powder and a stable Cr-rich oxide surface. The GARS powders were consolidated with LPBF. Process parameter maps identified a stable process window resulting in a relative density of 99.8%. Transmission electron microscopy and high-energy x-ray diffraction demonstrated that during LPBF, the stable phases in the powder dissociated in the liquid melt pool and reacted to form a high density (1.7 x 10(20)/m(3)) of homogeneously distributed Ti2Y2O7 pyrochlore dispersoids ranging from 17 to 57 nm. The use of GARS powder bypasses the mechanical alloying step typically required to produce ODS feedstock. Preliminary mechanical tests demonstrated an ultimate tensile and yield strength of 474 MPa and 312 MPa, respectively.

Automated summary

Laser powder bed fusion (LPBF) additive manufacturing is a promising method for fabricating oxide dispersion strengthened (ODS) steels. Gas atomization reaction synthesis (GARS) was used to produce 14YWT ferritic steel powders, which were then consolidated using LPBF. The resulting materials exhibited high density and uniform distribution of Ti2Y2O7 pyrochlore dispersoids. By using GARS powders, the need for mechanical alloying was eliminated, and preliminary mechanical tests showed high ultimate tensile and yield strength.